erskine-murray and j



J. ERSKINE-MURRAY AND J. ROBINSON. ELECTROMAGNETIC WAVE NAVIGATIONAL ARRANGEMENT.

AFPLlCATiON FILED 00129, 1919.

Patented May 24, 192

' 2 SHEETS-SHEET I.

A2? ll J. ERSKlNE-MURRAY AND J. ROBINSON.

ELECTROMAGNETIC WAVE NAVIGATIONAL ARRANGEMENT.

' APPucA oN FILED ecu-29,1919.

1,379,541. Patented May 24,1921;

2 SHEETS-SHEET 2.

Ii. ll

311M138 EBSKINE-MURRAY AND JAMES BRQBINSON, OI BIGGIN HILL, ENGLAND nLnoTnottAonm'io-We n NAVIGATIONAL ARRANGEMENT.

inmate l fipeeification of Letters Patent.

Patented May 24:; 192i.

inclination filed tic-toner 29, 1812. Serial I io. 33 1,3136.

it '0 a! whom it may concern.

Be it known that we, Mommy and JAMES RUBJNSUS, both subjects of the King of Great Britain, both residing in iliggi'n' llilhrlngland, have jOilIltly inrented certain new and nsei'iil lni oreinients in lllectroniagnetic-Ware i i-ungutional Arrnngex'nents, of which the following is a specification.

This invention reliites to the directive propagation of electromagnetic waves such tt'i those used in wireless telcgriiphy and ephony, and has for its principal object provide means whereby any ordnniry re iring station may be able to tfitlillttln with. curacy the direction from which electromagnetic waves emanating lion; a transmittin 'stntiomnsing apparatus n accordance wit: the present invention, reachsuclt re eeiring station. It will readily be'soen that vesselat seav or any aircraft fitted with Wireless apparatus which brings them within the range of a station or stations equipped hereinafter described will be able to use the directional information so obtained for any navigational purpose. 5

According to the invention directive s gnals are propagated from the sulllcc in pansof quickly succeeding individual signals at small time intervals, the individual signals of each p an being in different directions, not only from each other, as has been pro vionsly proposed, but also li oin the corresponding individual signals of the pro a mg pair of signals and of the succeeding an: 7 I

The direction of the soureecnn therefore be determined by it receiving station within range when the individual signals of u )itll of Slgnnlfi are of equal strength, for in such case the signals emanating from the source will be directed at pl'cdetcrminod angles on either'side of the reception po nt.

In the preferred arrangement according to this invention the pairs of signals are produced,- and may loo emitted directly, by a pair of coils which are orthogonally arranged and rotatable about their common central axis. The coils are coupled in Series with each other by an arrangement which permits the reversal of one of them with respect to the other. It will be seen that if e distinctive signal is sent out from the ui'iurce when those. coils occupy a (finite non one the receiving station has'means r determining, by timing or'otherwise,

JAMES Ensicinsthe angular displacement of the coils from tlnsdetinite position at the moment when the individual signals of u pailof signals are of equal strength and consequently only one of thecoils is etl'ective in producing indications at the reeeit ing station, the direction of the source of the signals can be obtained.

The invention will be hereinafter niore particularly described with reference to the .accon'ipanying diagrammatic drawings, wherein Figure 1 shows one arrangement of the sigi'lal emitting coils; Fig. 2 shows a n .i.'odificution in which these coils are stationary; Fig. 3 shows a further modification in which the-signal producing coils are associated with a pair of fixed acrials; Fig. l: shows an arrangement in which a rotatable or directive aerial is used in coniunction with fixed aerial; Fig. 5 is a znodificm tion of thislast arrangement in which the radiating elements are energized by a co1n-' bination of directive or rotatable coil and t fixed coil; Fig. (3 shows an arrangement in which a. pair of ael'ials at? a fixed angle are rotated; and Fig. 7 is a modificationoi this in which the radiating elements are fixed and are inductively energized by a. pair of rotatable coils.

in the arrangement of Fig. l, the radial:- m coils (6, Z) are at :1 fixed angle with respect to each other and are rotatable about their common central vertical axis. They are rotated step'l v-step or continuously at a definite speed and are alternately encrgized at ouch step or at definite time intervals or positions by the operation of switch 2" which connects the coils (I, I) alternately in a circuit containing a tuning condenser A: and inductive coil .s' through which the circuit is energized hy the oscillation circuit containing spark ga y, condenser m. and p-rinnu'y coil p. H distinctive signals are iicnt out from the source at definite positions of the coils (1., l), correspmlding for c umple to the cardinal points; of the compass mid the time interval or the number of pairs of signals lntcrwning between :1 distinctive or ordinal point" signal and the next pair of aignals of equal individual intensity is noted, the dirciclion of the signal source with respect to tho receiving station can be ascertained.

in Fig. 2 aerinls a, which are otherwisfQ identical, are equally spaced around a conr mon center (1 from which they radiato -They are connected in turn by means of a rotatable switch 1' with a. suitable -energizing arrangement represented by a secondary coil 8, primary 1), spark gap g and condenserm. The method of operation 15 sub stantially the same as fonthe' arrangement of Fig. 1, distinctive signals being sent at definite positions of the switch and, apart from these distinctive signals, pairs of signals are sent from equally spaced aerials as the Switch 1' is caused to traverse the system, the preferred order in which the several aerialsarc brought into action to produce such pairs of signals being 1, a; 2, 5' 3, 6; 4, 7; ,and so on around the circle. ltherwise stated, distinctive signals are sentat definite positions of the switch, 0. g. at the position or positions correspondlng with one or more cardinal points of the compass, and in addition signals are 'sent in pairs from equally spaced aerials with a minimum time interval between the individual signalsof each pair. Thus when the aerials are brought into action in the order hereinbefore specified, a signal with the switch 1' on aerial 1 would be followed immediately by a signal with the switch on aerial 4, and these wouldbe followed in turn by signals from aerials 2 and 5, I; and (S, and so on, a steady rate of progression of the switch '1- fronr aerial 1 to aerials 2, 3, 4, etc., being maintained.

in the arangcnient of Fig. 3, two fixed aerials u, a set at an angle (preferably a right angle) to each other have in their circuits inductive. coils i, '5' and tuning con densers f, ffrcspm-tivcly, the coils '1', i being arranged at the same angle to each other as the aerials a, (1 The. aerials are. energized in ditl'erential proportion by means of a rotatable inductive coil (1 according to the angular relation ofthis coil with the coils '1" respectively. The coil a witlrthe tuning condenser A i's connected with any suitable source of eli'etlrical oscillations, as ,for example in. the arrangement shown in the diagram.

If it should be. unneccssary to radiatv any considerable power the non-directable radiating systems of Fig. 3 may be dispensed with and a single direclable coil such as a used as the radiator of energy.

in both cases, in using the apparatus the coil 1!." is turned through a definite angle, say backward through 90, between the individual signals of each pair; then forward through a definite angle, say 91, for the first signal of the next pair and backward through 90 for the second signal thereof; and so on for each succeeding pair of signals, the distinctive or cardinal point signals being emitted as before at definite equally spaced points of the ompass.

In the arrangement of Fig. 4 a rotatable or directable aerial a and a fixed coil (1, which is connected inductively through coil 9 and variable inductance k with a fixed or non-directable aerial a, are connected in series in a circuit which also includes a tunsmall time intervals in different directions.

The radiating elements are energized by appropriate connection with any suitable source of electromagnetic oscillations, not shown in the diagram. 7

By noting at-the receiving station the interval that" has elapsed, either as measured by a stop watch or by the number of pairs of signals received between the reception of a pair of signals of equal individual strength and the distinctive signal immediately precedin or succeeding such pair of signals, the irection of the transmitting station from the receiving station can be ascertained.

This arrangement may be modified as shown in Fig. 5, to enable very considerably greater energy to be radiated by the introduction of two fixed radiating systems including aerials a, a set at right angles (preferably) to each other, inductive coils i, a" set at sameangle to each other-as the aerials, and tuning condensers f, f. These radiating circuits are energized inductively by a rotatable coil a, symmetrically arrangwl with respect to coils z, z" and connected in series with a fixed coil (5 which is inductively coupled with a nondirective aerial a". By means of switch 1* the interconnection of the coils a d is reversed at short intervals as the coil a is rotated continuously or step by step. A tuning condenser 7c is included in the circuit of coils a",

(I which is connected directly or inductively I with a suitable electromagnetic wave generator not shown in the diagram. e method of operation is as described with r ference to Fig. 4.

In the modified arrangement of Fig. 6, the two parts of the aerial a, a rotate at a fixed angle apart, preferably a righ angle,

about a common central vertical axis, a re-- verser 'I' automatically reversing their inter}. connection in the radiating circuit at short intervals as the coils'are rotated unidirectionally. The circuit, which includes a tuningcondenser is, is energized from any suitable, source, as for example, inductively through coil 8 from the oscillating circuit comprisin spark gap g,'condenser m and primary coil p. he precise mechanism effecting and correlating the rotation of the coils a a the operation of the switch 7 and the sending of the pairs of signals is no essential part of the present 1I1V8I1t10n, as the provision of pair of eoils before and alter sin-h mechanism is well within the eoinpass.

of any one skilled in the art. ihe eoils (I, a may, for example, be rotated step by step by meehanieal means at a deiinile rate, the switch 1* being reversed manually or auto matieally at oaeh step and the sending hey individual signals'ot eaeh pair of signals emitted are due in the radiation from the reversal rs- Speetively, and it \vill'bo obvious that when these are observed at the reeeiviug station as being of equal stre-Iugtlnoue oi the eoils is ineii'eetive and, in the .ZlHP of two eoils at right angles to eaeh other, will then be in a plane at right angles to the direeiion of propagation of the signal. oop led with this observation, the inl'ormation derivedfrom the. receipt of distinelive signals ei'nitted by the aerial at; definite points of. the eompass asthe coils (I, 1 are rotated, en ables the direelion oi the iransmitting slation to be aSLii'laiiZI-ilii.

For higher power radiation the n1odilication shown in Fig 'i' is used. This ar- .rangemeut will readily be understood williont further deseription. 'lhe aerials (r, 1/ seeondary eoils i Z and the rotatable induetive ('oils a, Z1" re set aiifthe same angle with eaeh other, preii'erabl at right angles. 'llhe noring eoils \vhieli are svnunetrieally plat-ed with respeet lo th ilfflktl eoils will be referred to as the main eoii and the auxiliary eoil respeeiivel); nd the driving meehanism eonsiscs o means for rotating these eoils at a uniform speed, or step by step. and means sueh as swileh r for revex-sing the eomneiions of the auxiliary eoil every degree or ball degriw, or as may bo arranged.

The observer allies reeeiring station will hear a sueeession of signals in pairs these pairs being usually oi unequal intensityx When the individual signals oi a pair are of equal strenglh, ihe in iinuiu direelion oi' propagaiion oi t l.

.l'rom the main eoi ireetiiy wward the observer. t the. transmission system requires say two mini-lies for a rotation ol 1%", and liiuix iiisiin 'nishiiw sigbe ele l is d Assuming in P" nals are sent out when the 5.. H1 eoil is in a pridetermined position, say due north and south, the observer will measure the time interval between. sueh distinguishing signal and the next, position of maximum radiation oi the main eoil. lie can then immediately calculate his bearings from the lame eon The use of n stopwateh is assumed in this method, but if distinguishing signals are sent out on a suiiieient number of predetermined direetions. 5a every 10* around the eonzpass', and the speed of rotation of the moving eoils is low enough to enable the observer to appreeiate eaeh separate pair of signals then the observer by eounting the number of pairs of signals reeeived between a distinguishing signal and the next sueeeeding position of equality of signals, the bearing run be found without the use of-a stopwateh. 1 lll5, l1()\\L\'LI'. involves a somewhat low speed of rotation, and it is found that with a very eonsiderabl inereased speed of rotation it possible to arrange eondiitions so that when the individual signals of eaeh pair of signals are of equalstrength a pure nole is hearth and when of unequal strength a series of harsh beats. With this method of using til apparatus a stopwatch is generally neeessarv to determine the time that elapses say from the nortn point distinguishing signal to the reeeption of the first pure note signal from that point It is to be noted that when two eoils are used in the apparatus which has been hereiin before deseribed, signals will be of equal intensii v when the main coil is pointing toward the reeeiviug station, and also when lhe auxiliary eoil is pointing in that direction. Thus, there will be tourpositions wherein signals are of equal intensity. The ambiguity thereby involved can, however. be annulled by arranging that the auxiliary call should have a eonside ably greater total area than the main eoil.

Having thus deseribed the nature of the said invention and the best means we know of earrying the. same into praet ieal effect, weelaiin l. The method of determining the bearing of a wireless transmitting station which eonsists in determining the interval bet-ween the reception of a distinctive signal periodieally propagated from the transmitting stat-ion in a definite direetion and the reeeption of a, pair of suecessive signals of equal. intensity in a series of signals propa gated from the transmitting station in pairs of ouielily sueeeeding individual signals at small equal fiime intervals, the individual signals of eaeh pair varying in relative intensity in a given direction with the position of a movable element which controls the emission of signals at the tansmitting station.

2. A wireless diluent-ion finding system comprising at the iransmititing station means including a rotating elementand a i&..

of the preceding pair of signals and of the succeeding pair, substantially as and for the purpose set forth.

3. In a wireless direction finding system, the combination of means at a transn'iitting station for periodically emitting distinctive I signals in definite directions with means in' cluding a rotatable element and a plurality or of radiating systems, one of which is the rotatable element, for emitting signals in pairs at small equal time intervals and for modifying the'relative' strength of the individual signals of each pair in a given dircction, substantially as described.

5. In a wireless direction finding system the combination at a transmittin r station of two wave producing circuits with a rotatable element controlling the direction of maximum strength ofsignals and means for reversing the inter-connection of the wave producing circuits, substantially as described.

In testimony whereof we have signed our names to this spccificathm.

JAMES EllSKlNlC-BIURRAY. JAMES RDBINSON. 

